Relationships and Evidence-Based Theoretical Perspectives on Persisting Symptoms and Functional Impairment Among Mild Traumatic Brain Injury and Behavioral Health Conditions

Neuropsychological Performance and Functional Capacity Following Mild Traumatic Brain Injury in Veterans

OBJECTIVE

To examine the relationship between neuropsychological functioning and performance-based functional capacity in veterans with a history of mild traumatic brain injury (mTBI), as well as the moderating effects of age and psychiatric symptoms on this relationship.

SETTING

Three Veterans Affairs medical centers.

PARTICIPANTS

One hundred nineteen Iraq/Afghanistan veterans with a history of mTBI and self-reported cognitive difficulties.

DESIGN

Cross-sectional, secondary data analysis of baseline measures in a randomized controlled trial.

MAIN MEASURES

The main outcome measure, functional capacity, was assessed using the objective and performance-based University of California San Diego Performance-based Skills Assessment-Brief. A global deficit score (GDS) was created as a composite score for performance on a battery of neuropsychological measures assessing domains of attention, processing speed, executive functioning, and verbal memory performance. Posttraumatic stress disorder (PTSD) symptom severity was assessed using the PTSD Checklist-Military Version, and depressive symptom severity was assessed using the Beck Depression Inventory, Second Edition.

RESULTS

Bivariate analyses indicated that worse neuropsychological performance (ie, higher GDS) and greater PTSD symptom severity were associated with worse communication abilities and worse overall functional capacity. Multiple linear regressions demonstrated that GDS and PTSD symptom severity explained 9% of the variance in communication and 10% of the variance in overall functional capacity; however, GDS emerged as the only significant predictor in both regressions. Age, PTSD, and depressive symptom severity did not moderate the relationship between GDS and overall functional capacity. Performance in the verbal learning and memory domain emerged as the strongest neuropsychological predictor of communication and overall functional capacity.

CONCLUSIONS

Worse neuropsychological functioning was moderately associated with worse performance-based functional capacity, even when accounting for PTSD symptom severity. Verbal learning and memory was the primary neuropsychological domain driving the relationship with functional capacity; improvement in verbal learning and memory may translate into improved functional capacity.

Preliminary Report: Localized Cerebral Blood Flow Mediates the Relationship between Progesterone and Perceived Stress Symptoms among Female Collegiate Club Athletes after Mild Traumatic Brain Injury

Female athletes are under-studied in the field of concussion research, despite evidence of higher injury prevalence and longer recovery time. Hormonal fluctuations caused by the natural menstrual cycle (MC) or hormonal contraceptive (HC) use impact both post-injury symptoms and neuroimaging findings, but the relationships among hormone, symptoms, and brain-based measures have not been jointly considered in concussion studies. In this preliminary study, we compared cerebral blood flow (CBF) measured with arterial spin labeling between concussed female club athletes 3-10 days after mild traumatic brain injury (mTBI) and demographic, HC/MC matched controls (CON). We tested whether CBF statistically mediates the relationship between progesterone serum levels and post-injury symptoms, which may support a hypothesis for progesterone's role in neuroprotection. We found a significant three-way relationship among progesterone, CBF, and perceived stress score (PSS) in the left middle temporal gyrus for the mTBI group. Higher progesterone was associated with lower (more normative) PSS, as well as higher (more normative) CBF. CBF mediates 100% of the relationship between progesterone and PSS (Sobel p value = 0.017). These findings support a hypothesis for progesterone having a neuroprotective role after concussion and highlight the importance of controlling for the effects of sex hormones in future concussion studies.

Cognition and Other Predictors of Functional Disability Among Veterans With Mild Traumatic Brain Injury and Posttraumatic Stress Disorder

BACKGROUND

Limitations in everyday functioning are frequently reported by veterans with a history of mild traumatic brain injury (mTBI) and/or posttraumatic stress disorder (PTSD). Multiple factors are associated with functional disability among veterans, including depression, poor social support, cognition, and substance use. However, the degree to which these factors, particularly cognitive capacities, contribute to functional limitations remains unclear.

METHODS

We evaluated performance on tests of processing speed, executive functioning, attention, and memory as predictors of functioning on the World Health Organization Disability Assessment Scale (WHODAS) 2.0 in 288 veterans. Participants were placed in one of the following groups: PTSD-only, mTBI-only, mTBI + PTSD, and neither PTSD nor mTBI (deployed control group). Cognitive test performances were evaluated as predictors of WHODAS 2.0 functional ratings in regression models that included demographic variables and a range of mood, behavioral health, and postconcussive symptom ratings.

RESULTS

Multiple cognitive test performances predicted WHODAS 2.0 scores in the deployed control group, but they generally did not predict functioning in the clinical groups when accounting for demographics, mood, behavioral health, and postconcussive symptoms.

CONCLUSIONS

In veterans with mTBI and/or PTSD, cognitive test performances are less associated with everyday functioning than mood and postconcussive symptoms.

Cutting to the Pathophysiology Chase: Translating Cutting-Edge Neuroscience to Rehabilitation Practice in Sports-Related Concussion Management

Mild traumatic brain injury, or concussion, is a common sports injury. Concussion involves physical injury to brain tissue and vascular and axonal damage that manifests as transient and often nonspecific clinical symptoms. Concussion diagnosis is challenging, and the relationship between brain injury and clinical symptoms is unclear. The purpose of this commentary was to translate cutting-edge neuroscience to rehabilitation practice. We (1) highlight potential biomarkers that may improve our understanding of concussion and its recovery, (2) explain why researchers must address the paucity of concussion research in female athletes, and (3) present female-specific factors that should be accounted for in future studies. Integrating objective, quantitative measures of concussion pathophysiology with concussion history, genetics, and genomics will help caregivers identify concussed athletes, tailor recovery protocols, and protect athletes from potential long-term effects of cumulative head impact. J Orthop Sports Phys Ther 2019;49(11):811-818. Epub 1 Jun 2019. doi:10.2519/jospt.2019.8884.